I have purchased L-supports from the factory. I have had about half of them set in place by a contracting company and now I have started fastening fence posts on the inside of the L-supports. Once I have set the posts, the contracting company will return to backfill the inside of the L-supports.
I have made a drawing (which is part of an approved building permit) of how the entire construction should look:
What you see in the drawing are 10kN L-supports that are 120 mm thick, as well as a fastened black post 95x95mm. The black post is actually pressure-treated and will be repainted in a year or two.
I was considering expansion bolts, but when I was at the building supply store this morning, they recommended facade plugs. So I bought myself a box and went home and started.
The work method was quite quick and smooth:
1. Temporarily attach the post where it should be with a clamp. 2. About 200mm from the bottom of the post: drill with a 10mm thick concrete drill with a hammer drill through both the 95-rule and 70-80 mm into the L-support's wall at the same time. 3. Carefully drive the plug into the hole with a hammer until the plug's collar is flush with the edge of the hole. 4. Screw in the accompanying screw with a screwdriver until the screwdriver can’t handle it anymore. 5. Release the clamp, adjust the post with a level in both directions, and fasten the clamp again. 6. Drill a new hole through the post and into the wall, about 150mm from the wall’s top edge. Insert the plug and screw. Also, make a third and final fastening in the same way between the bottom and top fastenings. 7. Tighten the screws fully with a socket wrench.
I am satisfied with the fastening, and it feels like the post is really secure. The L-supports step 200mm in height in some places due to level differences on the plot. Therefore, the fence will also step at the top. Where the plot slopes the most, there will be about 900mm visible L-support above ground. And where the plot levels out, there will only be about 300mm visible L-support above ground. The building permit states a maximum combined height of 2200mm for the L-support and fence. We will not build a 2200mm high fence everywhere. But what I want to say is that the fence on top of the L-supports can become as high as 1700mm.
To my questions:
1. Should I have used expansion bolts instead? Would it have been even stronger? It’s quite windy where I live, and there will not be larger gaps than 5mm between the boards, which probably makes the fence a large wind catcher. We will use 28x145mm facade boards on the fence.
2. I will set 50-60 posts. I have done about 9. On the first 5 posts, I forgot to use a washer. How bad is that? Do I need to redo those fastenings?
3. On one occasion, I got a thin but quite long crack in one corner of an L-support. What could I have done wrong then? Could it be because I put the screw in the plug and drove them both into the hole at the same time? And that the plug inside the hole then expanded too much? The drill hole closest to the crack is about 120mm from the top edge of the L-support and about 230mm from the right edge of the L-support's wall. What can I do to avoid more such cracks? What do I need to do with the crack to avoid problems in the future?
PS. Tagging @C.Lundin in this post as he has given me fantastic "concrete-related" help in a previous post. However, I truly appreciate everyone's answers <3
I would, if possible, have gone up further in length, to 180/200mm on the screw, and used larger washers.
Try to put washers on all. Tighten manually before backfilling.
The problem when drilling so far through both the post and concrete is that the post tends to move a little (even with clamps), which could cause the hole in the concrete to be a bit too large. But at the same time, it's a smart approach considering the number of posts.
Could the crack be due to the misfortune of hitting reinforcement?
If possible, I would have gone up in length, to 180/200mm on the screw, and used larger washers.
Try to put washers on all. Manually retighten before refilling.
The problem when drilling so far and through both the post and concrete is that the post wants to move a bit (even with clamps), which means the hole in the concrete might become a bit too large. But at the same time, it is a smart way considering the number of posts.
Could the crack be due to the bad luck of hitting reinforcement?
Regarding the length of the screw, I am terrified of accidentally drilling through the L-support wall or making more cracks since the wall will be visible to the street. It's possible that I hit reinforcement when it cracked; the drill bit I bought is apparently supposed to go through reinforcement too, according to the store. If I need even deeper drill holes for longer screws, isn't the risk even greater that I hit reinforcement or accidentally make a hole on the outside if I happen to drill too far or something...?
However, I could buy larger washers. So you think I should buy larger washers and attach / replace them on the 8 posts I've already installed?
Regarding retightening, do you mean that I should go there again and retighten all the screws with a socket wrench before they fill it in? No problem
It creates a pretty good leverage effect considering the height, and then the about 60mm in the wall doesn't feel that much. Can you figure out how the reinforcement is placed, so you can, for example, adjust the screw height?
Yes, somewhat larger washers (ByggMax sells at a good price in bulk) and washers in all places. And retighten with a socket wrench as you described.
The large area that forms is a real sail and will vibrate a little with the wind, causing the Profile to move. In your case, I would anchor up towards the lawn to ensure they remain in place for many years. It is not so much the earth pressure that does anything, it's the wind. Also, make sure there is crushed material between the soil and profile on the inside. Better to do something properly right away, instead of redoing it.
Hello and thank you for your responses and your time.
I just want to add that I have omitted some parts that are quite important, apologize for this, but here they are.
1. Trellis holes.
The fence will have a total length of 52 meters. In the fence, there will be 7 trellis holes that are 1.5m wide each and have about 10cm between the slats, which are just about 45mm wide. So we'll get some air passage there which will hopefully reduce the air pressure on the fence a bit. Below you can see how it all looks, including the trellis holes. (Apologies for the red lines which are the beginning of trying to sketch out where the posts and beams should be placed).
2. Angles.
The fence will follow our property line, with a few exceptions. There will be some angles in the fence, so it's not a straight 52-meter stretch. I think that helps make the whole thing a bit more stable. Here's the site plan (what we're discussing in this thread is section A - D, the darker red thicker lines are trellis holes):
In addition to what I mentioned above, the plan is to build a small cross wall in one place to conceal an air/water pump, so it will act as a strut to absorb pressure. We could do something similar in more places, like a trellis or something from the fence toward the property.
Furthermore, I plan to re-tighten with a wrench as you suggested before we backfill. We also plan to fill with some form of crushed stone, like 11 - 16, just under the posts before backfilling, to improve drainage around the posts.
I am well aware that the fence will act like a sail / large wind catcher. I've been worried about that since we started sketching this over a year ago. That's why I chose 10kN L-supports instead of 5kN. I also chose a 95-post instead of a 70-post. And of course, I want to do this properly from the start rather than redo it, especially when it has cost so damn much with L-supports and the cost for contractors to place the supports.
I should have posted this in the forum first to get opinions on the mounting. But when I was at the building supply store, they recommended this facade plug; I had been contemplating an expander for a long time. I hadn't thought of a washer until I tightened with a wrench and realized a washer is a must because the head eats into the post the more I tighten it.
Questions
1. Do I have to remove all the facade plugs I've already installed to use longer screws? 2. If the square washer I'm using (9x25x3mm Vfz) is too small, what size would be recommended? 3. If I leave the mounts I've already done untouched, could I add a fourth mount per post with, for example, a threaded rod + anchoring compound, or alternatively, an expansion bolt? Would that make any difference?
I'm looking for some form of "last resort help" here to avoid completely redoing the 16 posts I've already installed - if there's any form of supplementary securing that can be done. Also, I wonder, of course, how I should proceed. There will be roughly 52 posts, so I have quite a few left - which I can make sure to do the right way.
With the holes I've already made, I've occasionally encountered reinforcement. The drill I bought was supposedly able to drill through reinforcement, so the first time I pushed hard with the machine. And that might be when the crack appeared. After that, when encountering reinforcement, I chose to make a new hole a few centimeters beside to avoid the reinforcement.
1 Let the ones sitting there be
1a If you feel you need more grip, just add another, the kind you have will do fine.
2 For inadequate washers, they should be as large as possible. There are square galvanized ones available. If the hole is too big, place a smaller one outside.
3 See 1a
4 The notion of gravel behind the posts is good; place it directly against the posts with at least half a meter's width. A Platon mat or similar against the post and about 20 cm below it, up to just above the ground. This ensures the post never comes into direct contact with water and moisture in the soil, which would cause the post to rot despite being pressure-treated. I believe I know this about rotting.
5 The angles that form will provide good support, and if you can add another wing at 90 degrees somewhere, like a trash bin cover or something similar, then you're all set. You only need a few meters to brace against the wind. If possible, near a hole you'll have on the long stretch.
Edit The crack happened when you drilled and hit iron, causing everything to vibrate and resulting in a crack in the corner. It's nothing to worry about; the reinforcement holds it together.
Yes, I prefer not to move the ones I've set unless it's 100% necessary, I'm afraid that the screw won't hold as well if I unscrew it and then screw it back in.
1. Buy larger washers, but what size?
2. Supplement with an additional facade anchor with a corresponding screw and a large washer on each of the 16 posts I've already set. How close to existing holes is it safe to make new holes in concrete - so that the holes don't collapse into each other?
3. Then for the remaining 44 posts, I'll use the same 169mm screw with the corresponding anchor, but with new large washers. And I'll continue to install three per post.
4. Regarding backfilling, I understand that you're saying I should either use gravel/crushed stone OR a platonmatta? Because if I only use a platonmatta and mount it so that it extends "past" the post 20cm on each side and 20cm below the post, that should reduce its contact with moisture by about 95%? Then I shouldn't need to lay gravel next to it either? The reason I'm asking is that it seems much more convenient with a platonmatta. And cheaper
5. Regarding angles and cross walls. Then I'll set up a cross-wall where I intend to hide the pool pump. Then I can make a few more of those (with cross ties of 95 posts) which can also act as trellises for plants.
6. Then I forgot to mention this: Along roughly 40% of the fence stretch, I plan to have a deck. The L-supports end in height about 10 cm above the top edge of my intended deck. So I've thought about attaching beams (45x145) along with the 95 posts. Is it a bad idea to attach deck beams to the 95 posts mounted on the L-supports? It should make the 95 posts more secure. The deck will extend about 4 - 6 meters inward from the fence. So it will be quite a substantial deck (a lot of weight) supporting from the inside.
EDIT:
I updated the sketch a bit. Like this, with the deck against the fence, is the idea to build along a large part of the fence/L-supports. Hit or miss?
1 here is a good price https://www.proffsproduktershop.se/...BUmWMTH6LIzKB5RXAvD06KS004OAXa_kaAp0ZEALw_wcB
1a depending on the size of the bolt/screw you can take a smaller one and place it outside, Scroll on the same page
An alternative is a galvanized flat iron 60 mm and cut to 60X60 with a drilled hole that fits your bolt/screw
2 It works well with 50 mm between
3 Ok with that
4 Platon against the post and some gravel between the earth and platon, let's say 60 cm width, then it drains a bit towards the bottom, if water runs there during heavy rain
5 You decide yourself, just feel how steady or wobbly it gets, can be fixed with possibly braces later
6 It works perfectly fine to attach to the post, but you must have a certain number of footings to support the deck and with bearer beams and weight those L-profiles will be steady
1 here is a good price [link]
1a depending on what dim on bolt/screw you can take a smaller one and place outside, Scroll on the same page
An alternative is a galvanized flat bar 60 mm and cut it to 60X60 with drill holes that fit your bolt/screw
2 It is fine with 50 mm between
3 Ok with that
4 Platon against the post and some gravel between the earth and Platon, let's say 60 cm wide, then it will drain a bit towards the bottom if there is flowing water there during heavy rain
5 That you decide yourself, just feel how steady or wobbly it becomes, can be remedied with possibly, braces later
6 It's perfectly fine to attach to the post, but you must have a certain number of plinths that carry the deck and with beams and weight, those L-profiles will stand firm
1. The link you sent didn't have a specific washer marked. I have small washers from earlier that I already bought at the hardware store. But I plan to go to Byggmax tomorrow morning and buy a bunch of larger ones. Should I go for 6x6cm square washers galvanized?
2. I'll ask our contractor to throw gravel outside the Platon mat before they fill in with macadam/earth.
3. Regarding the attachment of the Platon mat, can special nails for Platon mat be attached to the L-supports? Do I need to pre-drill? Or is it enough if I attach the Platon mat to the side of each post and let the Platon mat hang out 20 cm on each side of the post? Or do I have to buy a bunch of Platon mat list?
4. Yes, the deck will not only rest on the beam that is placed along the fence's 95-posts. I also lay a lot of 300x300x50mm concrete plates for my beams to rest on (according to deck standard). I also attach the deck to the pool's concrete collar.
1 I can get that one. Screw it, take the largest you can find, perhaps you need your smaller ones so the screw doesn't go through the hole, preferably galvanized if you find it, not plain iron, stainless steel works too but galvanized/stainless steel don't get along that well, but it will probably last your lifetime.
2 If they're filling with macadam behind, no gravel is needed, it would be redundant then.
3 Just next put up the platon with anything on the post slightly. Just so it stays on. The backfill will pin it down.
4 A lot would have to happen for the L-profiles by the deck to move, there will be a cross brace sideways there.
We also installed L-supports and filled in the plot. Used 45x70 studs as fence posts with nail plugs. It didn't hold because the children hang on the fence. I used concrete screws; just drill, then blow clean, and finally fasten the bolts with the impact wrench. The nail plugs you used are electro-galvanized and will rust. They look too weak to hold those posts.
We also set L-supports and filled out the plot. Installed 45x70 studs as fence posts with nail plugs. It didn't hold because the kids hang on the fence. I put in concrete screws, just need to drill, then blow clean and finally fasten the bolts with the impact wrench. Those nail plugs you used are electro-galvanized and will rust. They look flimsy to hold those posts.
Hello and thank you for your reply
But it's not nail plugs, they're wall plugs where I first insert a plug and then screw the screw into the plug so that the plug expands. I'll call the builder's merchant tomorrow and ask why they are electro-galvanized, I wasn't aware / didn't think about it. But they recommended these to me when I told them what I was going to do, and I even showed pictures of the L-supports and the posts.
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GoForIt said:
